星形胶质细胞中TSPs对移植神经元环路重建作用研究

Heterogeneous population of reactive astrocytes in recipient brain dynamically affect the functionality of graft neurons, yet the detailed mechanism remains unclear. Neurotoxic A1 subtype astrocytes and neuronal protective A2 subtype of astrocytes each exert their functions through distinct sets of bioactive secretory factors. By studying reactive gliosis and functional integration of graft neurons in mice that received chemical lesion of striatal GABAergic neurons, we identified that Thrombospondins (TSPs) directly correlated to the gliosis and functional outcome of the neuronal transplantation, indicating that TSPs are involved in the heterogeneity of astrocytes, which certain subtype reactive astrocytes might promote the functional integration of the graft neurons through dynamic and heterogeneous expression of TSPs in certain circumstances. In this project, we will evaluate the effects of two reactive astrocyte subtypes on neuronal functional integration by transplantation of GABAergic medium spiny neuron derived from human embryonic stem cells in a striatal lesion model. We will investigate the existence of subtype astrocytes and re-expression of TSPs after brain injury, probe into the mechanisms of TSPs in the functional integration of the graft cell into the host brain, and use TSPs expression profile as readout to screen small molecules or drugs that can convert A1 astrocytes to A2 astrocytes. We will finally figure out the mechanisms underlying the functional integration of the graft cells, and identify those factors which would improve the neural reparation. These findings will further facilitate the translation of our current work into clinical application of the human stem cells.

神经细胞移植后，受体微环境中反应性星形胶质细胞的动态性和异质性，将直接影响移植神经元的存活及替代修复功能。具有神经毒性的A1型和具有神经保护作用的A2型星形胶质细胞可通过高表达不同的特定因子，促进或抑制神经元存活和突触形成。通过化学毁损小鼠纹状体，我们发现Thrombospondins（TSPs）家族的动态变化与胶质反应、移植神经元的修复能力高度相关，但TSPs与星形胶质细胞异质性是否相关尚不明确。本项目将通过向纹状体化学毁损的SCID小鼠脑内移植人胚胎干细胞分化的GABA神经元，比较损伤及移植后，各反应性胶质细胞亚型的状态及TSPs在两类胶质细胞的动态表达，探讨TSPs在神经环路重建中的作用及机制，并基于TSPs功能进一步发现促进星形胶质细胞亚型转换的因子。本研究将揭示星形胶质细胞影响移植神经细胞结构和功能整合的机制，建立促进神经修复的新策略，为推动神经损伤的干细胞替代治疗奠定基础。

神经细胞移植后，受体微环境中反应性星形胶质细胞的动态性和异质性，将直接影响移植神经元的存活及替代修复功能。具有神经毒性的A1型和具有神经保护作用的A2型星形胶质细胞可通过高表达不同的特定因子，促进或抑制神经元存活和突触形成。通过化学毁损小鼠纹状体，我们发现Thrombospondins（TSPs）家族的动态变化与胶质反应、移植神经元的修复能力高度相关，但TSPs与星形胶质细胞异质性是否相关尚不明确。本项目中首先分化了具备临床级特性的纹状体GABA能MSN神经元，作为后续移植治疗的基础。然后在体内和体外两种途径同时对星形胶质细胞的炎症反应进行类型鉴定和功能分析，解析其在细胞移植和整合微环境中可能发挥的作用。并通过向纹状体化学毁损的SCID小鼠脑内移植人胚胎干细胞分化的GABA神经元，比较损伤及移植后，各反应性胶质细胞亚型的状态及TSPs在两类胶质细胞的动态表达，探讨TSPs在神经环路重建中的作用及机制，并基于TSPs功能进一步发现促进星形胶质细胞亚型转换的因子。此外本项目还在上述基础之上构建了人源化星形胶质细胞嵌合工具鼠，为后续继续探索具有人源化特征的星形胶质细胞介导的移植微环境功能化提供研究基础。本项目的研究结果揭示星形胶质细胞影响移植神经细胞结构和功能整合的机制，建立了促进神经修复的新策略，为推动神经损伤的干细胞替代治疗奠定基础。